/**
 * 通用工具函数
 */

/**
 * 解析时间
 * @param {(Object|string|number)} time
 * @param {string} cFormat
 * @returns {string | null}
 */
export function parseTime(time, cFormat) {
  if (arguments.length === 0 || !time) {
    return null
  }
  const format = cFormat || '{y}-{m}-{d} {h}:{i}:{s}'
  let date
  if (typeof time === 'object') {
    date = time
  } else {
    if ((typeof time === 'string')) {
      if ((/^[0-9]+$/.test(time))) {
        // support "1548221490638"
        time = parseInt(time)
      } else {
        // support safari
        // https://stackoverflow.com/questions/4310953/invalid-date-in-safari
        time = time.replace(new RegExp(/-/gm), '/')
      }
    }

    if ((typeof time === 'number') && (time.toString().length === 10)) {
      time = time * 1000
    }
    date = new Date(time)
  }
  const formatObj = {
    y: date.getFullYear(),
    m: date.getMonth() + 1,
    d: date.getDate(),
    h: date.getHours(),
    i: date.getMinutes(),
    s: date.getSeconds(),
    a: date.getDay()
  }
  const time_str = format.replace(/{([ymdhisa])+}/g, (result, key) => {
    const value = formatObj[key]
    // Note: getDay() returns 0 on Sunday
    if (key === 'a') { return ['日', '一', '二', '三', '四', '五', '六'][value ] }
    return value.toString().padStart(2, '0')
  })
  return time_str
}

/**
 * 格式化时间
 * @param {number} time
 * @param {string} option
 * @returns {string}
 */
export function formatTime(time, option) {
  if (('' + time).length === 10) {
    time = parseInt(time) * 1000
  } else {
    time = +time
  }
  const d = new Date(time)
  const now = Date.now()

  const diff = (now - d) / 1000

  if (diff < 30) {
    return '刚刚'
  } else if (diff < 3600) {
    // less 1 hour
    return Math.ceil(diff / 60) + '分钟前'
  } else if (diff < 3600 * 24) {
    return Math.ceil(diff / 3600) + '小时前'
  } else if (diff < 3600 * 24 * 2) {
    return '1天前'
  }
  if (option) {
    return parseTime(time, option)
  } else {
    return (
      d.getMonth() +
      1 +
      '月' +
      d.getDate() +
      '日' +
      d.getHours() +
      '时' +
      d.getMinutes() +
      '分'
    )
  }
}

/**
 * 格式化文件大小
 * @param {number} bytes
 * @returns {string}
 */
export function formatFileSize(bytes) {
  if (bytes === 0) return '0 B'
  const k = 1024
  const sizes = ['B', 'KB', 'MB', 'GB', 'TB']
  const i = Math.floor(Math.log(bytes) / Math.log(k))
  return parseFloat((bytes / Math.pow(k, i)).toFixed(2)) + ' ' + sizes[i]
}

/**
 * 防抖函数
 * @param {Function} func
 * @param {number} wait
 * @param {boolean} immediate
 * @returns {Function}
 */
export function debounce(func, wait, immediate) {
  let timeout, args, context, timestamp, result

  const later = function() {
    // 据上一次触发时间间隔
    const last = +new Date() - timestamp

    // 上次被包装函数被调用时间间隔 last 小于设定时间间隔 wait
    if (last < wait && last > 0) {
      timeout = setTimeout(later, wait - last)
    } else {
      timeout = null
      // 如果设定为immediate===true，因为开始边界已经调用过了此处无需调用
      if (!immediate) {
        result = func.apply(context, args)
        if (!timeout) context = args = null
      }
    }
  }

  return function(...args) {
    context = this
    timestamp = +new Date()
    const callNow = immediate && !timeout
    // 如果延时不存在，重新设定延时
    if (!timeout) timeout = setTimeout(later, wait)
    if (callNow) {
      result = func.apply(context, args)
      context = args = null
    }

    return result
  }
}

/**
 * 节流函数
 * @param {Function} func
 * @param {number} wait
 * @returns {Function}
 */
export function throttle(func, wait) {
  let timeout
  return function() {
    const context = this
    const args = arguments
    if (!timeout) {
      timeout = setTimeout(() => {
        timeout = null
        func.apply(context, args)
      }, wait)
    }
  }
}

/**
 * 深拷贝
 * @param {*} source
 * @returns {*}
 */
export function deepClone(source) {
  if (!source && typeof source !== 'object') {
    throw new Error('error arguments', 'deepClone')
  }
  const targetObj = source.constructor === Array ? [] : {}
  Object.keys(source).forEach(keys => {
    if (source[keys] && typeof source[keys] === 'object') {
      targetObj[keys] = deepClone(source[keys])
    } else {
      targetObj[keys] = source[keys]
    }
  })
  return targetObj
}

/**
 * 数组去重
 * @param {Array} arr
 * @returns {Array}
 */
export function uniqueArr(arr) {
  return Array.from(new Set(arr))
}

/**
 * 获取文件扩展名
 * @param {string} filename
 * @returns {string}
 */
export function getFileExtension(filename) {
  return filename.slice((filename.lastIndexOf('.') - 1 >>> 0) + 2)
}

/**
 * 生成随机ID
 * @param {number} length
 * @returns {string}
 */
export function generateId(length = 8) {
  return Math.random().toString(36).substr(2, length)
}

/**
 * 滚动到顶部
 * @param {number} duration
 */
export function scrollToTop(duration = 500) {
  const start = window.pageYOffset
  const startTime = performance.now()

  function scroll() {
    const now = performance.now()
    const time = Math.min(1, (now - startTime) / duration)
    const timeFunction = 1 - Math.pow(1 - time, 3)
    window.scroll(0, Math.ceil(timeFunction * (0 - start) + start))

    if (time < 1) {
      requestAnimationFrame(scroll)
    }
  }

  requestAnimationFrame(scroll)
}

/**
 * 复制到剪贴板
 * @param {string} text
 * @returns {Promise}
 */
export function copyToClipboard(text) {
  if (navigator.clipboard) {
    return navigator.clipboard.writeText(text)
  } else {
    // 兼容旧浏览器
    const textArea = document.createElement('textarea')
    textArea.value = text
    document.body.appendChild(textArea)
    textArea.focus()
    textArea.select()
    try {
      document.execCommand('copy')
      document.body.removeChild(textArea)
      return Promise.resolve()
    } catch (err) {
      document.body.removeChild(textArea)
      return Promise.reject(err)
    }
  }
}

/**
 * 检查是否为移动设备
 * @returns {boolean}
 */
export function isMobile() {
  return /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent)
}

/**
 * 获取URL参数
 * @param {string} name
 * @returns {string|null}
 */
export function getUrlParam(name) {
  const reg = new RegExp('(^|&)' + name + '=([^&]*)(&|$)')
  const r = window.location.search.substr(1).match(reg)
  if (r != null) return unescape(r[2])
  return null
}
